1. Field of the Invention
The present invention relates to a plasma etching method and a plasma etching apparatus for forming a plasma of an etching gas and etching a SiC layer formed on a processing object.
2. Description of the Related Art
Conventionally, a plasma etching method has been widely used in a manufacturing process and the like of a semiconductor device. In the plasma etching method, it has been known to use an etching gas consisting of a mixed gas of CHF3 and N2 for selectively etching a SiC layer formed on a processing object with respect to an oxide layer (SiO2 layer) which constitutes an insulation layer (for example, refer to Japanese Patent Laid-open Application No. 2004-140025).
Recently, in a manufacturing field of the semiconductor device, as an oxide layer constituting an insulation layer, for example, SiOC ((CDO)Carbon-doped oxide) etc. as a so called Low-k film having a lower dielectric constant have been used.
However, when an etching gas consisting of a mixed gas of CHF3 and N2 was used, when etching the SiC layer, it was impossible to obtain a sufficient selectivity to the SiOC layer. Thus, there was a problem that the selection ratio (etching rate of SiC layer/etching rate of SiOC layer) becomes to about less than 2.